1. Field of the Invention
The present invention refers to a method for the precise measurement of dependency on amplitude and phase of a plurality of high frequency signals, preferably in the synchrotron accelerator of elementary particles, and a device for carrying out said method.
2. Description of the Related Art
Modern synchrotron accelerators of elementary particles, and in particular the sources of the synchrotron light, set up very strict demands as to the accuracy, repeatability and resolution when measuring the position of the accelerated elementary particles in the direction transversal to the direction of motion thereof. Said measurements must particularly meet requirements of sub micron resolution, of high accuracy which is independent of the current intensity of the accelerated particles, of repeatability of measurements during a longer period of time, of the uninterrupted transmission of measurements in real time during the regular operation of the accelerator, and of transmitting of a plurality of series broadband measurements with the sampling frequency that generally exceeds a million samples per second. Said measurements are of vital importance at the startup of the accelerator, and an indispensable diagnostic when optimizing and studying the operation of the accelerator.
Multichannel measuring devices mostly do their job with success; however, they share a common disadvantage reflecting in intermittence and time variability of transfer functions of each channel resulting in limiting the repeatability of measurements. In the document U.S. Pat. No. 5,001,416 there is disclosed a solution which has solved the required repeatability of the orbit position by means of time division multiplexing. The drawback of said solution lies in the narrow frequency bandwidth of the measuring device allowing only a slow correction of the orbit. In addition, due to the nature of the time division multiplexing said device disclosed in U.S. Pat. No. 5,001,416 is susceptible to unwanted mapping of the frequency band. All the recurrent effects of the synchrotron accelerator in the frequency range above the period of the time division multiplex may coincide distorting therewith the information about the real orbit.
Further on, in the document U.S. Pat. No. 6,972,552 there is described a non-multiplexing four channel measuring method for comparing the amplitudes of high frequency signals which removes the disadvantage of frequency mapping. It consists of four channel high frequency analogue amplifier, analogue-digital (A/D) converter and digital calculating circuit for signal processing. The measuring device acquires the required precision and the symmetry of the input analogue part by means of switching the four amplifying channels for all four measured signals. By switching the channels the device figures out the differences of amplification thereof and takes them into account when calculating the position. Further on, the document U.S. Pat. No. 6,972,552 describes additional reducing of the remaining error by filtering the signals in the immediate proximity of the channel switching frequency and by aperiodic channel switching. The filtering procedure, however, additionally reduces the error but at the same time makes the measuring device insensible in the same frequency range. On the contrary, the procedure of frequency distribution of errors by aperiodic channel switching preserves the sensibility of the measuring device but it does not remove the remaining error. Ideally, this solution would require very frequent channel switching which, however, is in contradiction with the disadvantage of the described method that causes the transition effect every time the channels switch. The error produced therein is proportional to the frequency of switching.